Ocular imaging of the fundus provides clinicians with a unique opportunity to non-invasively study the internal system of blood vessels that provide for retinal circulation within the eye. Conveniently, analysis of such ocular images provides a good way for clinicians to monitor retinal pathologies that threaten sight as well as conditions, such as diabetes and hypertension, for example, which generally affect circulation through blood vessels in the body.
In general terms, various pathological conditions tend to be associated with changes in the morphological and geometrical characteristics of blood vessels, such as increases in width (caliber) and tortuosity during congestion, within the eye. Pathological conditions also tend to be associated with blob-like structures such as hemorrhages and exudates. Examination of retinal images is predominantly carried out qualitatively by clinicians, and it is generally true to say that the process of retinal image analysis is extremely time-consuming. A further drawback is that conventional analytical techniques are generally highly subjective—that is to say that it is not unusual for different clinicians to derive different information from the same ocular image.
In the context of retinopathy of preterm infants, there is a window of opportunity for treatment that is in the region of twenty-two to seventy-two hours, and in this context in particular and indeed more generally it would be advantageous if the process of analyzing retinal images could be automated to provide accurate, repeatable and fast ocular analysis, in particular insofar as measurements of ocular blood vessels are concerned.